This invention lies in the field of particulate sodium alpha olefin sulfonate (Na AOS) compositions.
There is a need in the art of synthetic detergent formulations for a particulate form of Na AOS whose physical characteristics would make it compatible with other ingredients commonly employed in synthetic detergent formulations (syndets). This need arises out of the circumstance that syndets are commonly compounded for particular end use applications, so that an individual syndet can vary in terms of relative percentages of ingredients and in terms of ingredients present. This dictates the flexibility of the compounder; for example, the larger the percentage of inert material present with a particulate Na AOS the more limited would be the use field in which such a diluted Na AOS can be used. Each detergent formulation typically contains many different components; see "Chemical and Process Technical Encyclopedia" pp. 345-352, McGraw Hill Book Company (1974).
Specifically, in order to prepare the class of surfactants known as sodium alpha olefin sulfonates in such a suitable particulate form whose physical characteristics would make is compatible with other ingredients commonly employed in synthetic detergent formulations, various efforts have been made to dry aqueous solutions and suspensions of this class of pure surfactant without known commercial success. Sodium alpha olefin sulfonate (sometimes herein referred to as NaAOS) characteristically, upon being spray or drum dried in a substantially pure form, appears to characteristically demonstrate severe problems of thermoplasticity, tackiness, free flowability, insufficient flake or bead strength characteristics, hygroscopicity, and the like, regardless of drying conditions. At the present time, it does not appear generally possible to dry, as by drum or spray drying on a commercial scale, aqueous solutions or slurries of substantially pure NaAOS so as to produce a particulate product comprised substantially of just NaAOS which has suitable physical properties for commercial blending.
Particularly when a dried, particulate form of NaAOS is to be used in compounding syndets, it is not necessary for such a particulate NaAOS to have by itself good syndet properties, such as, for example, for laundry use; good syndet properties can be achieved for a laundry syndet by subsequent compounding using technology and know-how well known in the art.
The problems of preparing a particulate system rich in NaAOS are compounded by the fact that NaAOS is characteristically somewhat hygroscopic. Thus, for example, if a slurry of NaAOS is spray-dried, the product beads will usually slowly take up moisture from the surrounding air over a period of time which makes such pure NaAOS beads, which have been stored in air for a period of time characteristically, somewhat undesirable for use in formulating synthetic detergents. Moisture absorption and inherent thermoplasticity tend to result in agglomeration in packout, thus yielding a non-pourable product. In addition, spray drying of a slurry rich in NaAOS invariably results in severe adhesion of product on the walls of the drying chamber as well as in product conveying lines thus creating a significant yield loss in product packout, equipment fouling problems, and, more importantly, a potential fire hazard within the drying unit.
Somewhat better results in producing a commercially suitable particulate form of NaAOS have apparently been heretofore achieved in this art at least experimentally by incorporating into an aqueous solution or suspension of NaAOS which is to be spray or drum-dried quantities of some other inert (from a detergent composition standpoint) material, preferably one which is commonly used in detergent formulations, such as sodium sulfate. However, to date, so far as is how known, no one has heretofore ever been able to produce on a commercial scale a particulate form of intermediate surfactant material which is rich in NaAOS, which can be substantially completely comprised of active (from a detergent composition standpoint) components, and which, still at the same time, not only has a combination of physical properties making such particulate form compatible with other particulate agents commonly available and commonly used in formulating synthetic detergents, but also can be used in detergent formulating by simple dry blending techniques to produce an innumerable variety of synthetic detergent compositions intended for respective various specific end use applications and needs.
For example, a drum dried sodium alpha olefin sulfonate product is commercially available, but this product contains appreciable quantities of diluents, such as sodium chloride and sodium sulfate, as well as an additive to suppress dusting and "firm up" the flake. The presence of the diluents tends to limit syndet compounding applications.
Grant U.S. Pat. No. 3,950,276 teaches a phosphate-free laundry syndet composition containing olefin sulfonate, sodium silicate, non-ionic surfactant, and carboxymethyl cellulose. The Grant teachings contain no suggestion of a two-component bead type intermediate composition having utility as an intermediate in formulating synthetic detergent compositions, such as phosphate-free laundry syndet compositions.
Parke et al U.S. Pat. No. 3,759,834 convert drum dried olefin sulfonate to moisturized, translucent flakes through the addition thereto of water followed by milling. The post-adding of free water to drum dried NaAOS to make flakes does not teach or suggest dry, free flowing intermediate compositions for syndet compounding and does not solve the problem of providing a bead-type concentrate product suitable for multiple syndet compounding applications.